Potential.java

/* *****************************************************************************
 *  Name:              Ada Lovelace
 *  Coursera User ID:  123456
 *  Last modified:     October 16, 1842
 **************************************************************************** */

import java.awt.Color;

public class Potential {
    public static Charge[] readCharges() {
        int n = StdIn.readInt();
        Charge[] charges = new Charge[n];
        for (int i = 0; i < n; i++) {
            double x0 = StdIn.readDouble();
            double y0 = StdIn.readDouble();
            double q0 = StdIn.readDouble();
            charges[i] = new Charge(x0, y0, q0);
        }
        return charges;
    }

    public static Color toColor(double val) {
        val = 128 + val / 2.0e10;
        int i = 0;
        if (val > 255) i = 255;
        else if (val >= 0) i = (int) val;
        // i = i * 37 % 255;
        return new Color(i, i, i);
    }

    public static void main(String[] args) {
        Charge[] charges = readCharges();
        int size = 800;// StdIn.readInt();
        Picture pic = new Picture(size, size);
        for (int col = 0; col < size; col++) {
            for (int row = 0; row < size; row++) {
                double val = 0.0;
                for (int k = 0; k < charges.length; k++) {
                    double x = 1.0 * col / size;
                    double y = 1.0 * row / size;
                    val += charges[k].potentialAt(x, y);
                }
                pic.set(col, size - 1 - row, toColor(val));
            }
        }
        pic.show();
    }
}